This invention relates to a mechanism for exerting a pressurized sanding force on a vehicle surface, particularly an electro-coated, primed or freshly painted vehicle surface.
During painting operations on newly manufactured vehicles it is a conventional practice to sand the vehicle surface after the application of a color coat to the surface, and prior to the application of clear coat. The sanding operation is sometimes performed by a human technician while the vehicle is moving along a predetermined path in a paint booth.
On problem with conventional sanding practice is that it is difficult for the human technician to develop a consistent and satisfactory sanding pressure on the vehicle surface. The present invention relates to a robotic sanding mechanism wherein a rotary sanding disk is moved along a predetermined path on the vehicle surface while exerting a controlled pressure on the surface being sanded.
The robotic sanding mechanism comprises a robotic support structure that is lockable to, or tracks, the vehicle while the vehicle is moving along a predetermined path (or is stationary) and a sanding head that can change its angulation in accordance with changes in the vehicle surface contour. The sanding head supports a rotatable sanding disk that can rotate in various different planes, e.g. vertical, horizontal or at various angulations between the horizontal and vertical, in accordance with the changing vehicle contour.
The sanding head comprises a carriage that can move on a line normal to the surface being sanded, and a force responsive means that maintains a relatively constant pressure between the sanding disk and the vehicle surface being sanded. This force-responsive means is operable whatever the orientation of the sanding disk, i.e. horizontal, vertical, or various intermediate angulations.
The sanding head preferably includes means for supplying aerated water and or ambient air to the sanding disk, whereby the sanding disk is prevented from undergoing an undesired vacuum-lock grip relation to the vehicle surface being sanded. The sanding disk can remain in operable frictional contact with the vehicle surface without becoming disconnected from the sanding disk mounting device.
The sanding head may be designed to reduce an undesired vacuum lock action that can occur between the sanding disk and the vehicle surface. Special passages in the head introduce air into the interface between the sanding disk and vehicle surface, to reduce or eliminate the undesired vacuum lock action.
In preferred practice of the invention, an automatic means is provided for removing a worn sanding disk from the sanding head, and replacing the worn disk with a new sanding disk. This feature keeps the robotic sanding mechanism in synchronism with a line of moving vehicles, such that the vehicle conveyour system can remain in continuous operation, even when it is necessary to replace a worn sanding disk.
Specific features of the invention will be apparent from the attached drawings and description of an illustrative embodiment of the invention.